Mold device, electronic apparatus, and electronic apparatus manufacturing method

ABSTRACT

In a mold device comprising pin members provided projecting from an upper mold or a lower mold in order to form an electronic apparatus frame of a metallic material having pores arranged at given pitches, the pin members are arranged so that a center line connecting the adjacent pin members is not perpendicular to the direction of introduction of a molten metal into a cavity of the mold device.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This is a continuation of application No. PCT/JP99/03238, filed Jun. 17, 1999.

[0002] This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 10-174978, filed Jun. 22, 1998, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0003] This invention relates to a configuration of a light metal frame of an electronic apparatus, such as a personal computer, a manufacturing method for manufacturing the electronic apparatus frame, and a mold device.

[0004] Recently, magnesium alloys have been mainly used as the material of an electronic apparatus frame of a light metal. These alloys are molded by die-casting or thixotropy. These molding methods use different equipment mechanisms. In either method, however, an alloy melted at 580° C. to 750° C. is injected into a mold of about 100° C. to 350° C. and molded.

[0005]FIG. 6 shows a configuration of a conventional electronic apparatus frame. In this electronic apparatus frame, a molten metal is poured through a sprue 2, for use as a molten metal inlet portion (a portion corresponding to the shape of the electronic apparatus frame just molded will be described with reference to this drawing), and the molten metal is introduced into a desired mold through a runner 3. The introduced molten metal diffuses throughout a cavity 4 and finally reaches air vents 5. Further, a molten metal reservoir 6 is coupled to the air vents 5. When the molten metal is introduced through the sprue 2, therefore, air can be discharged to the outside through the air vents 5. Thereupon, the frame can be formed without containing any voids therein.

[0006] This electronic apparatus frame sometimes may be provided with a large number of pores 7 that are arranged at given pitches and serve to discharge heat to the outside or serve as a speaker for external sounding.

[0007] Generally, in this case, the pores 7 are arrayed like a lattice, as shown in FIGS. 6 and 7, in order to keep spaces between the pores uniform.

[0008] Conventionally, in order to form the pores 7 in this array, a molded piece molded by means of a mold device 1 is stamped out, in some cases. Alternatively, pin members 8 in a latticelike array are previously formed projecting from the inside of the cavity 4 of the mold device 1, as shown in FIG. 7. In this case, the molten metal is introduced into the cavity 4 to be solidified therein. The pores 7 in this latticelike array are formed by doing this.

[0009] In general, the pores 7 are arranged at narrow pitches in order to prevent foreign matter from getting into the frame. Therefore, postforming the molded piece with the narrow pitches after the removal from the mold device 1 in the aforesaid manner requires labor and cost depending on the number of pores.

[0010] Thus, the pin members 8 are previously arranged at narrow pitches in the mold device 1. Since the molten metal introduced into the mold is rapidly cooled and solidified when it touches the inner wall surface of the cavity 4, however, its fluidity is not satisfactory in the case where a large number of pin members 8 are arranged at narrow pitches, in particular.

[0011] More specifically, the molten metal may be solidified as it passes straight between the rows of the pin members 8, as indicated by arrows in FIG. 7, possibly failing to get into gaps 9 between the pin members 8 that constitute the rows.

[0012] Thus, the molten metal fails to penetrate into the regions between the pin members 8 and forms unfilled portions, so that the pores 7 cannot be formed in the given array, and substantial unfilled portions are formed inevitably.

BRIEF SUMMARY OF THE INVENTION

[0013] This invention has been contrived in consideration of these circumstances, and its object is to provide a mold device, having an array of pin members capable of improving the fluidity of a molten metal therein, and a manufacturing method for an electronic apparatus frame based on this array of pin members.

[0014] According to a preferred embodiment, a mold device of this invention is a mold device comprising pin members provided projecting from a first mold or a second mold in order to form an electronic apparatus frame of a metallic material having pores arranged at given pitches, the pin members being arranged so that a center line connecting the closest adjacent pin members is not perpendicular to the direction of introduction of a molten metal into a cavity of the mold device.

[0015] Further, an electronic apparatus manufacturing method of this invention is an electronic apparatus manufacturing method for molding an electronic apparatus including a frame of a metallic material having pores arranged at given pitches, by means of a mold device, comprising a flowing process for diffusing a molten metal throughout the interior of the mold device, and a solidifying process for solidifying the molten metal introduced into the mold device in the flowing process, thereby forming the frame, the mold device being the aforementioned mold device.

[0016] Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0017] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention.

[0018]FIG. 1 is a perspective view showing the shape of a prior art electronic apparatus frame;

[0019]FIG. 2 is a view showing a prior art array of pin members and flows of a molten metal;

[0020]FIG. 3 is a perspective view showing a configuration of a portable computer as an electronic apparatus according to one embodiment of this embodiment;

[0021]FIG. 4 is a view showing a state of a pin member array in a mold device of the same embodiment and illustrating the way rows of pin members are shifted for half the pitch in the direction perpendicular to the direction of introduction of a molten metal;

[0022]FIG. 5 is a view showing a state of a pin member array in the mold device of the same embodiment and illustrating the way rows of pin members are shifted for half the pitch in the direction parallel to the direction of introduction of the molten metal;

[0023]FIG. 6 is a view showing a state of a pin member array in a zigzag form;

[0024]FIG. 7 is a side sectional view showing a configuration of a mold device of the same embodiment;

[0025]FIG. 8 is a perspective view showing a configuration of an electronic apparatus frame of the same embodiment; and

[0026]FIG. 9 is a view showing a state in which the direction of introduction of the molten metal is inclined at a given angle to a latticelike array of pin members according to a modification of this invention.

DETAILED DESCRIPTION OF THE INVENTION

[0027] One embodiment of the present invention will now be described with reference to FIGS. 3 to 8.

[0028]FIG. 3 is an external view showing the shape of a portable computer 10 such as a note-type personal computer. In this drawing, the portable computer 10 comprises a computer body 11 and a display unit 12 that is rockably supported on the computer body 11. The computer body 11 is provided with a frame 13, and this frame 13 is designed so that a lower frame 14 and an upper frame 15 are suitably joined by means of, for example, screws or the like. However, the lower frame 14 and the upper frame 15 may be joined by means of any other arrangement than this.

[0029] In the description to follow, the frame that is applied to the portable computer 10 or some other electronic apparatus will be described as an electronic apparatus frame 20. The following description is based on FIGS. 4 to 8.

[0030] The electronic apparatus frame 20 of the light metal personal computer, formed of a magnesium alloy, for example, is formed having a large number of pores 21 arranged at short pitches. The pores 21 serve to cool the inside of the personal computer or serve as a speaker for external sounding.

[0031] These numerous pores 21 can be formed by introducing a molten metal into a mold device 30, which will be described below.

[0032] The mold device 30 includes an upper mold 31 as a first mold and a lower mold 32 as a second mold, which engage each other to form the mold device 30. The mold device 30 is provided with a sprue 33, for use as a molten metal inlet, and a runner 34 for guiding the molten metal in introduction into the mold device 30 and in uniform diffusion. The molten metal guided by means of the runner 34 is introduced into a cavity 35 of the mold device 30.

[0033] Although the molten metal is a molten magnesium alloy, it may be replaced with any other alloy, such as an aluminum alloy.

[0034] Pin members 36 are provided in those portions of the cavity 35 which correspond to the pores 21 of the electronic apparatus frame 20 in order to form the pores 21 in the electronic apparatus frame 20. The pin members 36 are formed having the following array in the cavity 35 of the mold device 30, compared with the conventional latticelike array.

[0035] If the distance between each two adjacent ones of the pin members 36 that are arranged like a lattice is a, in the array of the pin members 36 of the present invention, as shown in FIG. 4, one row of pin members 36, out of each two adjacent rows of pin members 36 perpendicular to the flow of the molten metal, is shifted for half the pitch with respect to the other row of pin members 36.

[0036] Accordingly, the distance between the adjacent pin members 36, which is conventionally adjusted to a, as shown in FIG. 4, changes into b (=a×{square root over (5/2)}) according to the Pythagorean theorem. Thus, the distance between the adjacent pin members 36 can be made longer than in the case where the pin members 36 are arranged like a lattice.

[0037] As this is done, the flow rate of the molten metal that can flow between the pin members 36 can be made higher than in the case of the conventional latticelike array, that is, the molten metal can be made ready to flow.

[0038] In this case, the pin members 36 are staggered for half the pitch, and the flow of the molten metal is not changed at all. Therefore, the molten metal can thread through the widened spaces between the pin members 36.

[0039] In this array of the pin members 36, the pin members 36 are arrayed in zigzag.

[0040] However, the array of the pin members 36 is not limited to this arrangement. As shown in FIG. 5, one row of pin members 36, out of each two adjacent rows of pin members 36 (parallel to the flowing direction of the molten metal in this case), may be shifted for half the pitch with respect to the other row of pin members 36.

[0041] In this case also, the distance between the adjacent pin members 36 changes from the conventional value a into (=a×{square root over (5/2)}), as shown in FIG. 5. Thus, the distance between the adjacent pin members 36 can be made longer than in the case where the pin members 36 are arrayed like a lattice so that the molten metal are ready to flow.

[0042] The zigzag array is not limited to the case where the pin members 36 are arrayed in zigzag so that they are staggered for half the pitch, and may be applied to various other cases. More specifically, the basic array may be made rectangular instead of being in the form of a lattice. A zigzag configuration shown in FIG. 6, which has an angle different from that of FIG. 4, can be obtained by staggering the pin members 36 for half the pitch from the basic array in the longitudinal or crosswise direction (the rectangular basic configuration is shifted for half the pitch in the longitudinal direction so that the pin members 36 in the zigzag array form a lattice inclined at a given angle in FIG. 6).

[0043] In this case, #1 and #4, #2 and #4, #4 and #6, of the pin members 36 are located closest to one another. In this case also, the zigzag array allows the molten metal to penetrate into gap portions 37 between the pin members.

[0044] In this case also, a center line that connect the closest adjacent pin members 36 is not perpendicular to the flowing direction of the molten metal and crosses it diagonally at a given angle. Accordingly, the distance between the pin members 36 can be made longer than in the case where the adjacent pin members 36 are arranged at right angles to the flow. Thus, the pin members 36 can be prevented from hindering the molten metal flow, so that the flow rate of the molten metal can be increased.

[0045] Further, the pin members 36 are arranged so that each two adjacent rows of pin members 36 extend at right angles to or parallel to the flowing direction of the molten metal and that the other side row of the pin members 36 is shifted substantially for half the pitch. However, the amount of shift of the pin members 36 is not limited to about half the pitch, and may be set at any value provided that the molten metal can be caused to flow satisfactorily in positions between the pin members 36.

[0046] The molten metal is introduced into the mold device 30 arranged in this manner through the sprue 33, diffused through the runner 34, and introduced into the cavity 35. In this case, the molten metal is diffused by means of the runner 34 as it is introduced into the cavity 35, so that the molten metal uniformly flows parallel in the cavity 35. Further, the molten metal is introduced substantially parallel to the inner wall surface of the cavity 35.

[0047] In this case, a pressure of about 250 tons, for example, is applied to the molten magnesium alloy, and the introduction is carried out to perform injection molding of the electronic apparatus frame 20.

[0048] By this introduction, the molten metal can be diffused throughout the regions between the pin members 36 that are arranged in the aforesaid manner. Thus, the molten metal can be caused to penetrate also into the gap portions 37 between the adjacent pin members 36, as shown in FIGS. 4 to 6.

[0049] In the regions where the pin members 36 are arranged, therefore, the cavity 35 can be filled with molten metal without forming any unfilled portions, and thereafter, the molten metal reaches air vents 38.

[0050] The air vents 38 serve to discharge air in the mold device 30 to the outside, and a molten metal reservoir 39 further communicates with the air vents 38. Thus, the molten metal introduced into the mold device 30 can reach the molten metal reservoir 39 without producing voids in the cavity 35.

[0051] The temperature of the mold device 30 ranges from about 100° C. to 350° C., which is lower than the temperature of the molten magnesium alloy ranging from about 580° C. to 750° C. When the molten metal is introduced into the cavity 35, therefore, the molten metal is immediately cooled and solidified as it touches the mold device 30.

[0052] However, the molten metal is subjected to the pressure as it is introduced, as mentioned before, and the pin members 36 are arrayed in the aforesaid manner. Accordingly, the molten metal reaches the air vents 38 before it is solidified, and thereafter, the molten metal is solidified.

[0053] After the molten metal is solidified, the upper mold 31 and the lower mold 32 are released from engagement, and a molded piece is pushed out by means of an ejector pin. Thereupon, the electronic apparatus frame 20 having the pores 21 formed corresponding to the aforesaid array of the pin members 36 is formed. Thus, in this array of the pores 21 also, the distance between each two zigzagged or adjacent pores 21 is elongated.

[0054] Basically, however, the number of pores 21 formed in the same area is fixed, and there is no hindrance to the functionality of heat release from the pores 21 and the diffusibility of sound from the pores 21 as the speaker.

[0055] According to the manufacturing method for the mold device 30 and the electronic apparatus frame 20 constructed in this manner, the pin members 36 are arranged so that one row of pin members 36, out of each two adjacent rows of pin members 36 that extend at right angles to or parallel to the direction of introduction of the molten metal into the cavity 35, is shifted substantially for half the pitch with respect to the other row of pin members 36. Accordingly, the space between the adjacent pin members 36 can be widened.

[0056] Thus, the molten metal can be circulated at a higher rate in the regions between the pin members 36, and the molten metal can be caused more smoothly to thread through the spaces between the pin members 36 than in the case where the pin members 36 are arrayed like a lattice.

[0057] Accordingly, the molten metal can be diffused also throughout the gap portions 37 between the pin members 36 without forming any unfilled portions.

[0058] Thus, the resulting electronic apparatus frame 20 has no unfilled portions and suffers no malformation, so that the yield of the electronic apparatus frame 20 can be improved.

[0059] If the pin members 36 are arrayed in any other zigzag form than the one in which the other side of the adjacent pin members 36 is shifted substantially for half the pitch in the aforesaid manner, a center line connecting the adjacent pin members 36 is not perpendicular to the flow of the molten metal. In this case also, therefore, the flow rate of the molten metal can be made higher than in the case where the pin members 36 are arrayed like a lattice.

[0060] In the case where the pin members 36 are arrayed in zigzag, as compared with the case where the pin members 36 are arrayed in a lattice, moreover, the adjacent pin members 36 are not arranged parallel to the flowing direction of the molten metal. Accordingly, the molten metal can be caused easily to penetrate into the gap portions 37 between the pin members 36. Thus, formation of unfilled portions and malformation of the electronic apparatus frame 20 can be prevented.

[0061] According to the arrangement in which the pin members 36 are arranged so that one row of pin members 36, out of each two adjacent rows of pin members 36 that extend at right angles to the direction of introduction of the molten metal into the cavity 35, is shifted substantially for half the pitch with respect to the other row of pin members 36, in particular, the pin members 36 can prevent the molten metal from flowing in a straight line so that the molten metal meanders between the pin members 36. Thus, the molten metal can be allowed to penetrate particularly satisfactorily into the spaces between the pin members 36.

[0062] Although the one embodiment of the present invention has been described above, the present invention can be modified variously. The following is a description of the modification.

[0063] According to the embodiment described above, the pin members 36 are arrayed in a zigzag form such that the other of the adjacent rows of the pin members 36 is shifted substantially for half the pitch or in any other zigzag form. Alternatively, however, the pin members 36 may be arrayed like a lattice such that the direction of introduction of the molten metal is inclined at a given angle to the pin members 36 in this array, as shown in FIG. 9, for example.

[0064] In this case also, a flow of the molten metal can be produced such that the molten metal threads through the spaces between the pin members 36, as indicated by arrows in FIG. 9. Thus, in the case where the pin members 36 are arrayed like a lattice, the molten metal can be diffused throughout the gap portions 37 between the pin members 36 by inclining the direction of introduction of the molten metal.

[0065] Further, various modifications may be effected without departing from the spirit of the present invention.

[0066] Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. 

What is claimed is:
 1. In a mold device comprising pin members provided projecting from a first mold or a second mold in order to form an electronic apparatus frame of a metallic material having pores arranged at given pitches, said pin members being arranged so that a center line connecting the closest adjacent pin members is not perpendicular to the direction of introduction of a molten metal into a cavity of the mold device.
 2. In a mold device comprising pin members provided projecting from a first mold or a second mold in order to form an electronic apparatus frame of a metallic material having pores arranged at given pitches, said pin members being arranged so that one row of pin members, out of each two adjacent rows of pin members, is shifted substantially for half the pitch in the direction thereof with respect to the other row of pin members.
 3. In a mold device comprising pin members provided projecting from a first mold or a second mold in order to form an electronic apparatus frame of a metallic material having pores arranged at given pitches, said pin members being arranged in a zigzag array.
 4. In a mold device comprising pin members provided projecting from a first mold or a second mold in order to form an electronic apparatus frame of a metallic material having pores arranged at given pitches, said pin members being arranged in zigzag with respect to the direction of introduction of a molten metal.
 5. An electronic apparatus manufacturing method for molding an electronic apparatus including a frame of a metallic material having pores arranged at given pitches, by means of a mold device, comprising: a flowing process for diffusing a molten metal throughout the interior of said mold device; and a solidifying process for solidifying the molten metal introduced into the mold device in said flowing process, thereby forming the frame, said mold device being the mold device according to any one of claims 1 to 4 .
 6. In an electronic apparatus including an electronic apparatus frame of a metallic material having pores arranged at given pitches, said electronic apparatus frame being formed by casting.
 7. An electronic apparatus according to claim 6 , wherein said metallic material is magnesium. 